A damper provides a damping force in reaction to motion. In one particular installation, a damper within a steering system provides a damping force to the steering components of a vehicle. A steering damper is typically used to reduce or eliminate uncontrolled steering movements, steering system input caused by the roadway or impact of objects with the tires, underdamped oscillation of the steering system, and/or other undesired effects on the control or steering feel of a vehicle. The addition of a steering damper to a vehicle can also alleviate driver fatigue by reducing the effort required to maintain the steering wheel at the desired steering input.
The damper is generally mounted to span a moving component of the steering system and another vehicle component, often a stationary component, such as the frame of the vehicle. In this regard, a steering damper is typically a through-shaft type damper, having a shaft extending the length of the damper body, with a mounting point at one end of the shaft, and a second mounting fixture integrated with or attached to the body of the damper. Through-shaft steering dampers provide advantages in this context by exhibiting balanced damping characteristics in both damping directions, and often provide increased shaft range over conventional dampers.
Through-shaft dampers require an additional sealing point over a non-through-shaft damper as a result of the shaft extending through both ends of the damper body. In damper configurations using a secondary gas (e.g. nitrogen gas) chamber in addition to the damping fluid chamber, an intermediate floating piston or dividing bladder is often used to separate the gas and damping fluid. In these types of dampers, the gas provides a positive pressure that reduces the tendency for cavitation of the hydraulic damping fluid, can be compressed to allow for thermal expansion, and provides a means for adjustment of the characteristics of the damper by changing the pressure of the gas. In conventional through-shaft dampers, the intermediate floating piston or dividing bladder is generally located in the damper body or in a remote reservoir. In the through-shaft configurations without a remote reservoir, the sealing surfaces of the interface where the shaft passes through the damper body must create a seal on the shaft between the gas and the atmosphere. Due to the difficulty of sealing gas from the atmosphere, and the relatively high velocity and displacement of the shaft with respect to the seal, the particular seal location is prone to premature failure, allowing the gas to escape, or allowing contaminants to ingress the secondary chamber. Conversely, a remote reservoir setup removes the need for such a seal, but requires additional packaging space and is typically more expensive to manufacture.
Therefore, a need exists for an improved through-shaft steering damper, without resorting to an external reservoir, that eliminates the need to seal the gas chamber from the atmosphere along the shaft of the damper. Embodiments of the present disclosure are directed to fulfilling these and other needs.